since jpegs can be trivially embedded in pdf documents without changes to the data stream this is the first image format we will support. currently this is a naive approach which doesn't share an image resources between pages. ideally we will either de-duplicated images when added, return a re-usable key once an image is added, or both.
an encoding array in an adobe type 1 font may be missing its declaration ending in 'for', if we encounter 'dup' while looking for the 'for' token we have a special case to go straight into reading the encoding.
also handles a case where the page content stream contains a path-closing operator without any path being active.
since inline image data may contain the end image "ei" token inside the data stream there's no reliable way to actually determine if we've read all the data. for this reason if we end up with an invalid state parsing operations after we've read the end image token we try to recover by reading from the previous token to the next end image token if any. we supply log information to let the consumer know this is what we're doing. it's still not bullet-proof but it should be good enough.
also support negative page rotation values by adding them to a 360 degree rotation so -90 degrees clockwise is 270 degrees clockwise.
when a marked content region contains an image we load it eagerly since we won't have access to the necessary classes at evaluation time. we also default image colorspace to the active graphics state colorspace if the dictionary doesn't contain a valid entry.
since the properties in marked content may be indirect references or belong to the page resources array, the value should be calculated during content processing. this change tidies up the marked content classes so they do not expose mutable data and uses the pdf token scanner overloads to load dictionary data.
since an inline image's data stream may contain the characters 'ei' as a result of compression it's possible to read an end image operator mid-data, this results in the next operator also being end image and the content stream being in an invalid state. to recover from this when we detect this situation we remove the previous operator, read to the current operator and replace the operator and data bytes in the list of operations.
if the font descriptor uses the fromsubtype flag the actual type of the font can differ from that specified in the font dictionary. in this case a truetype font actually contains a type1c, compact font format, font. in this case we fall back to using the type1 parser.
also handles a closesubpath command appearing without any path construction operators.
the 3 font types mentioned are moved to the new fonts project, any referenced types are moved to the core project. most truetype classes are made public #8.
to make the project more useful and expose more usable classes we're rearchitecting in the following way. code used to read fonts from external file formats like truetype, adobe font metrics (afm) and adobe type 1 fonts are moving to a new project which doesn't reference most of the pdf logic. the shared logic is moving to a new flat-structured project called core. this is a sort-of onion type architecture, with core being the... core, fonts being the next layer of the onion, pdfpig itself the next. this will then support additional libraries/projects as outer layers of the onion as well as releasing standalone version of the font library as pdfbox does with fontbox.
this starts to add logic for per-character mapping of unicode characters to byte values for truetype fonts in the pdf document builder. in order to support unicode characters outside the 0-255 range when creating new pdf documents without using composite fonts, we need to map values outside these range into this range. to do this we start at 1 and map each character we encounter to the next code, up to a maximum of 255. we provide a custom tounicode cmap in the font dictionary which maps these byte values, 0-255, back to unicode code points (short).
we also provide a custom firstchar, lastchar and widths array for the font mapping just the values we use.
since fonts no longer contain just the latin character set the font descriptor enum is set to have the symbolic flag set. this means values will be looked up in either the mac-roman (1, 0) or windows-symbol (3, 0) cmap tables (these cmap tables are distinct from cmap tables in the pdf file) inside the actual truetype font bytes. this means the currently generated font file is invalid, because while the widths array and tounicode cmap return the correct values the actual font itself returns whatever values where in those positions before the remapping occurred.
in order to fix this we will need to override the windows-symbol cmap contained in the underlying truetype font to match our mapping. this will be a lot of work and involve significant rewriting of the font file itself, in order to preserve checksum integrity.
also adds a gitignore entry for the 'benchmark' subfolder in tools where custom benchmarking applications can be built and run without being added to source control.
resources such as fonts are linked to page content operations using name labels, e.g. "/F1", these resource labels can be reassigned on different pages or inside form xobjects. we now clear the entire resource state for each page which is parsed and after form xobject operations which use resource dictionaries.
support both xobject and inline images. adds unsupported filters so that exceptions are only thrown when accessing lazily evaluated image.bytes property rather than when opening the page.
treat all warnings as errors.
an inline image in a pdf content stream starts with the bi tag, then id declares the start of image data and ei the end. attempting to parse the bytes after the id tag as usual resulted in errors. this change adds special case handling for inline images.
previously if no matching unicode was found for a character code we would return a null letter. instead we now map from the character code directly to a character. this seems to work for most documents, except where there are ligatures, e.g. fi or ff, but is still better than not returning anything.
point size was previously only calculated based on the transformation matrix but now uses the transformation matrix, the rotation matrix and the font matrix values. the calculated value still seems unlikely to be correct so it is exposed using the page's experimental access for now, rather than as a public getter.
- begin adding support for extended graphics state (the 'gs' operator) including setting the font #39.
- apply page level rotation to the glyph bounding box and width to get correct glyph sizes #41.
- wrap page rotation in a value type to ensure the value is restricted to right angle rotations and provide convenience members #42.
- fix bug where system font finder never worked for truetype fonts because it began reading the file from the wrong offset.
